Injection pumps and perfusors are used for the controlled dispensing of medical active ingredients, which may be, e.g., drugs or anesthetics that enter the patient's bloodstream. Vapors are frequently used in the case of anesthetics that enter the patients respiration circulation, the so-called inhalation anesthetics. In the case of perfusors, the liquid medical active ingredients are pushed forward by the piston of a syringe at an exactly defined rate. The rates of delivery are approximately 0.5 mL to 20 mL per hour. While no mixtures, but at most an individual anesthetic is administered in the case of anesthetics, the dispensing of 10 or more different drugs for one patient is not a rarity. Additional drugs are sometimes also added during a therapy. Every individual drug is diluted differently with a carrier liquid, e.g., a Ringer's solution. In light of technical defects, the pressure and the output of the pump is usually monitored. Based on the compliance of the tubes, errors caused by other factors, e.g., reduced rates of dispensing, which may be caused by stenosis in the patient, are detected only with a certain time delay.
If the rate of dispensing is changed for a medical active ingredient, the time period until effectiveness appears in the patient cannot be precisely determined because of the compliance of the entire system, because if different drugs are dispensed by means of injection pumps and integrated in a bank of stopcocks, the time period until an individual drug becomes effective is additionally determined by the overall volume flow from all injection pumps between the bank of stopcocks and the patient's bloodstream. The medical active ingredient and the carrier solution are usually drawn up manually in the syringes for the injection pumps and perfusors, labeled and introduced. A rate of dispensing is subsequently set. It is obvious that human error may become a cause for a nonoptimally adapted medication in such a situation.
The infusion device with central control device and a plurality of infusion apparatus for liquid medical active ingredients, which better meets the safety requirements according to the above explanations, is known from Utility Model No. DE 299 22 736 U1. In the case of the infusion device, each infusion apparatus has an unmistakable code number, which is sent to a control device, which will then send corresponding signals to the infusion apparatus. Precautions are thus taken against an error in dispensing. However, the problem of accurately determining and changing the rates of dispensing still remains to be solved.